1. Field of Invention
The subject disclosure relates to spa monitoring and control circuitry for portable spas, tubs and the like and more particularly to voltage sensing circuitry for determining the magnitude, frequency and zero cross times of an input signal, and to circuitry for timing the opening and closing of heater relays to occur at or near zero cross points.
2. Related Art
Portable spas have become quite popular as a result of their ease of use and multiplicity of features such as varied jet and seating configurations. One area where the inventor has recognized that improvement would be desirable concerns the manner of efficiently maintaining and controlling various spa equipment operations, and particularly the operation of the spa water heater and associated relays.